Constraint on neutrino masses from SDSS-III/BOSS Ly-alpha forest and other cosmological probes

International audienceWe present constraints on the parameters of the $\Lambda$CDM cosmologicalmodel in the presence of massive neutrinos, using the one-dimensionalLy$\alpha$ forest power spectrum obtained with the Baryon OscillationSpectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS) byPalanque-Delabrouille et al. (2013), complemented by additional cosmologicalprobes. The interpretation of the measured Ly$\alpha$ spectrum is done using asecond-order Taylor expansion of the simulated power spectrum. BOSS Ly$\alpha$ data alone provide better bounds than previous Ly$\alpha$ results,but are still poorly constraining, especially for the sum of neutrino masses$\sum m_\nu$, for which we obtain an upper bound of 1.1~eV (95\% CL), includingsystematics for both data and simulations. Ly$\alpha$ constraints on$\Lambda$CDM parameters and neutrino masses are compatible with CMB bounds fromthe Planck collaboration. Interestingly, the combination of Ly$\alpha$ with CMBdata reduces the uncertainties significantly, due to very different directionsof degeneracy in parameter space, leading to the strongest cosmological boundto date on the total neutrino mass, $\sum m_\nu < 0.15$~eV at 95\% CL (with abest-fit in zero). Adding recent BAO results further tightens this constraintto $\sum m_\nu < 0.14$~eV at 95\% CL. This bound is nearly independent of thestatistical approach used, and of the different combinations of CMB and BAOdata sets considered in this paper in addition to Ly$\alpha$. Given themeasured values of the two squared mass differences $\Delta m^2$, this resulttends to favor the normal hierarchy scenario against the inverted hierarchyscenario for the masses of the active neutrino species

Les variétés : pivots de la filière blé dur

International audienceLe choix de la variété figure parmi les premières étapes de l'itinéraire technique, Il concerne aussi toute la filière. Selon le terroir, c'est-à-dire l'environnement biophysique, (sol, climat, bioagresseurs), et selon le système de culture (dont l'itinéraire technique) dans lequel elle est cultivée, la variété joue un rôle déterminant sur la quantité et la qualité du produit fini. Elle participe par conséquent au revenu de l'ensemble des acteurs de la filière.La variété doit satisfaire au cahier des charges du marché visé, aux objectifs et aux contraintes des agriculteurs. La priorisation des caractéristiques recherchées dépend de l'acteur qui la sélectionne, de la réglementation qui s'applique et des dynamiques sociétales (figure 5.1).Selon le marché visé, selon la filière et donc selon les acteurs, la variété recherchée diffère. La sélection d'une variété est donc une étape majeure qui nécessite d'associer tous les acteurs d'une filière à la définition des variétés qui conviennent (idéotypes)

Azimuthal asymmetries of charged hadrons produced by high-energy muons scattered off longitudinally polarised deuterons

International audienceAzimuthal asymmetries in semi-inclusive production of positive (h (+)) and negative hadrons (h (-)) have been measured by scattering 160 GeV muons off longitudinally polarised deuterons at CERN. The asymmetries were decomposed in several terms according to their expected modulation in the azimuthal angle phi of the outgoing hadron. Each term receives contributions from one or several spin and transverse-momentum-dependent parton distribution and fragmentation functions. The amplitudes of all phi-modulation terms of the hadron asymmetries integrated over the kinematic variables are found to be consistent with zero within statistical errors, while the constant terms are nonzero and equal for h (+) and h (-) within the statistical errors. The dependencies of the phi-modulated terms versus the Bjorken momentum fraction x, the hadron fractional momentum z, and the hadron transverse momentum p(n)(T) were studied. The x dependence of the constant terms for both positive and negative hadrons is in agreement with the longitudinal double-spin hadron asymmetries, measured in semi-inclusive deep-inelastic scattering. The x dependence of the sin phi-modulation term is less pronounced than that in the corresponding HERMES data. All other dependencies of the phi-modulation amplitudes are consistent with zero within the statistical errors

Quark helicity distributions from longitudinal spin asymmetries in muon–proton and muon–deuteron scattering

International audienceDouble-spin asymmetries for production of charged pions and kaons in semi-inclusive deep-inelastic muon scattering have been measured by the COMPASS experiment at CERN. The data, obtained by scattering a 160 GeV muon beam off a longitudinally polarised NH3 target, cover a range of the Bjorken variable x between 0.004 and 0.7. A leading order evaluation of the helicity distributions for the three lightest quarks and antiquark flavours derived from these asymmetries and from our previous deuteron data is presented. The resulting values of the sea quark distributions are small and do not show any sizable dependence on x in the range of the measurements. No significant difference is observed between the strange and antistrange helicity distributions, both compatible with zero. The integrated value of the flavour asymmetry of the helicity distribution of the light-quark sea, View the MathML sourceΔu¯−Δd¯, is found to be slightly positive, about 1.5 standard deviations away from zero

The spin-dependent structure function of the proton g(1)(p) and a test of the Bjorken sum rule

International audienceThe inclusive double-spin asymmetry. A(1)(p), has been measured at COMPASS in deep-inelastic polarised muon scattering off a large polarised NH3 target. The data, collected in the year 2007, cover the range Q(2) > 1 (GeV/c)(2), 0.004 < x < 0.7 and improve the statistical precision of g(1)(p)(x) by a factor of two in the region x < 0.02. The new proton asymmetries are combined with those previously published for the deuteron to extract the non-singlet spin-dependent structure function g(1)(NS)(x. Q(2)). The isovector quark density, Delta q(3)(x, Q(2)), is evaluated from a NLO QCD fit of g(1)(NS). The first moment of Delta q(3) is in good agreement with the value predicted by the Bjorken sum rule and corresponds to a ratio of the axial and vector coupling constants vertical bar g(A)/g(V)vertical bar = 1.28 +/- 0.07 (stat.) +/- 0.10 (syst.)

Measurement of the Collins and Sivers asymmetries on transversely polarised protons

International audienceThe Collins and Sivers asymmetries for charged hadrons produced in deeply inelastic scattering on transversely polarised protons have been extracted from the data collected in 2007 with the CERN SPS muon beam tuned at 160 GeV/c. At large values of the Bjorken x variable non-zero Collins asymmetries are observed both for positive and negative hadrons while the Sivers asymmetry for positive hadrons is slightly positive over almost all the measured x range. These results strongly support the present theoretical interpretation of these asymmetries, in terms of leading-twist quark distribution and fragmentation functions

Observation of a J(PC)=1(-+) Exotic Resonance in Diffractive Dissociation of 190 GeV/c pi(-) into pi(-)pi(-)pi(+)

International audienceThe COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi(-)pi(-)pi(+) final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420 000 events taken at values of the squared 4-momentum transfer t(l) between 0.1 and 1 GeV2/c(2). The well-known resonances a(1)(1260), a(2)(1320), and pi(2)(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC) = 1(-+) at 1.66 GeV/c(2) decaying to rho pi. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC) = 2(-+) and 1(++) waves. From a mass-dependent fit a resonance mass of (1660 +/- 10(-64)(+0)) MeV/c(2) and a width of (269 +/- 21(-64)(+42)) MeV/c(2) are deduced, with an intensity of (1.7 +/- 0.2)% of the total intensity

Neutrino masses and cosmology with Lyman-alpha forest power spectrum

We present constraints on neutrino masses, the primordial fluctuation spectrum from inflation, and other parameters of the \u39bCDM model, using the one-dimensional Ly\u3b1-forest power spectrum measured by [1] from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS-III), complemented by Planck 2015 cosmic microwave background (CMB) data and other cosmological probes. This paper improves on the previous analysis by [2] by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size, by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium, by including additional freedom to account for systematic uncertainties, and by using Planck 2015 constraints in place of Planck 2013. Fitting Ly\u3b1 data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data, except for a weak tension on the scalar index ns. Combining BOSS Ly\u3b1 with Planck CMB constrains the sum of neutrino masses to 11 m\u3bd < 0.12 eV (95% C.L.) including all identified systematic uncertainties, tighter than our previous limit (0.15 eV) and more robust. Adding Ly\u3b1 data to CMB data reduces the uncertainties on the optical depth to reionization \u3c4, through the correlation of \u3c4 with \u3c38. Similarly, correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations r. The tension on ns can be accommodated by allowing for a running dns/d ln k. Allowing running as a free parameter in the fits does not change the limit on 11 m\u3bd. We discuss possible interpretations of these results in the context of slow-roll inflation